S7 communication −  Performant data communication via Industrial Ethernet. Communication is based on standard TCP/IP −  Ethernet access via an RJ45 socket −  Simple connection to an S7-200 system via the S7-200 bus −  Facilitates a flexible and distributed automation structure  −  Remote programming, configuration and diagnostics of an S7-200 system (e.g. program upload and download or status displays) via Industrial Ethernet and STEP 7 Micro/WIN 32. −  Basis for simple further processing and archiving of process data −  Enables simultaneous communication with up to 8 S7 controllers −  Provides a connection to S7-OPC −  Simple network administration −  Modules can be exchanged without requiring repeat program-ming/configuration (plug & play) −  S7 communication services, "XPUT/XGET", as client and server −  S7 communication services, "READ/WRITE", as server •  Watchdog timer The CP 243-1 is equipped with a Watchdog circuit. The Watchdog starts each time CP 243-1 starts up. Typically, the Watchdog monitoring time is 5 s. Due to component-related tolerances, this time can increase to 7 s. If the Watchdog monitoring time sets in, a reset of the CP 243-1 is automatically brought about. This restarts the CP 243-1. During this time, the CP 243-1 reports a "Parity Er-ror" to the S7-200 CPU. Handling of this type of error is described in the STEP 7 Micro/WIN 32 documentation. •  Address assignment via preset MAC address (48 bit value).  The MAC address is assigned to each CP 243-1 at the factory. It is printed on a label affixed to the underside of the upper door. An IP address can be assigned to the CP 243-1 via the preset MAC address us-ing the BOOTP protocol.    2.2  S7 communication via Industrial Ethernet 2.2.1  Application The S7 communication via Industrial Ethernet makes program-controlled commu-nication via communication SFBs/FBs and configured S7 connections possible. The CP 243-1 supports S7 communication via Industrial Ethernet by means of the XPUT/XGET and READ/WRITE services. In general, up to 212/212 bytes of user data can be transmitted per command. However, if the CP 243-1 is being operated as a server, up to 222 bytes can be transmitted per read operation.
The CP 243-1 supports up to 8 communication channels to clients or servers on one or more remote communication partners. The CP 243-1 operates according to the client/server principle per channel. Per channel, only one command at a time is received, processed and responded to with a positive or negative response. Only after a response has been sent will the CP 243-1 accept another command. If the CP 243-1 receives more than one command on a channel configured as a server, only the first command is processed and the following commands are ig-nored until the transaction is completed, i.e. until a response has been sent. The CP 243-1 is not equipped with channel-specific command management and does not buffer commands. Prerequisites for communication with a PC/PG As before, the S7-200 CPU can still be accessed by a PG/PC via the PPI interface. In addition, it can also be accessed via the CP 243-1 through Ethernet. The follow-ing prerequisites must be met to use this alternative: −  An Ethernet card is inserted in the PG/PC and configured, and there is an Ethernet or TCP/IP connection to the CP 243-1 (possibly through routers, firewalls, ...) −  STEP 7 Micro/WIN 32, version 3.2.1 or higher, is installed on the PC/PG. −  The CP 243-1 has been assigned a valid IP address. This address can be defined in the configuration or retrieved from a BOOTP server via the BOOTP protocol. At this time, only one STEP 7 Micro/WIN 32 can simultaneously communicate with the S7-200 CPU via a CP 243-1. 2.2.2  Types of communication The CP 243-1 is provided with three types of communication relationships that can be applied either inpidually or in combination. 1.  Connection to STEP 7 Micro/WIN 32 2.  Connection to further, remote components of the SIMATIC S7 family 3.  Connection to OPC-based applications on a PC/PG 2.2.3  Communication partners •  S7-200 CPU with CP 243-1 •  S7-300 CPU with CP 343-1 or CP 343-IT •  S7-400 CPU with CP 443-1 or CP 443-IT •  PG/PC with OPC server •  PG/PC with STEP 7 Micro/WIN 32 In the STEP 7 HW-Config program, you can identify which types of S7-300 CPUs and S7-400 CPUs support the S7 protocol, XPUT/XGET, and, hence, which ones can communicate with the CP 243-1. When you select an S7-300 or S7-400 CPU in the catalog window in the program, the selected CPU must support the "S7 communication" function. For systems in the S7-300 series, XPUT/XGET can only be operated via Ethernet with a communications processor of version 1.1 or higher. You can identify the communications processor version by looking at the MLFB number, among other things. If you use a CP 343-1, the MLFB number must contain the sequence "EX11“. The CP 443-1 ISO cannot communicate with the CP 243-1, since the CP 443-1 ISO do not have TCP/IP and RFC 1006 on board. Attention Only one CP 243-1 should be connected per S7-200 CPU. It cannot be guaranteed that the S7-200 system will operate properly if additional CP 243-1 are connected. Note When communicating with an OPC server, it should be noted that the CP 243-1 does not support the service that automatically queries which objects are present in the S7-200 (e.g. DBxx...).     S7-200自动化系统英文文献和中文翻译(2):http://www.youerw.com/fanyi/lunwen_52483.html